Primordial black holes (PBHs) formed from the collapse of large density perturbations in the very early universe [1]}, [2]}, [3]}, [4]} can contribute to the cold dark matter (CDM) and provide a possible explanation [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]}, [15]}, [16]}, [17]}, [18]}, [19]}, [20]}, [21]} to the gravitational-wave (GW) events from the mergers of binary black holes detected by LIGO-Virgo collaboration [22]}, [23]}.
